To read and write magnetic disk files, transducing heads are mounted on a series of parallel arms which are in turn connected to a tower for holding them, which in turn is connected to a rail or carriage structure the opposite end of which carriage structure is connected to a voice coil. This entire actuator assembly is movable in response to the energization of the voice coil in a voice coil motor. Connecting the voice coil directly to the actuator assembly results in longitudinal resonances and vibrations which do not allow for accurate location of the transducing heads above tracks on the disk media.
It is understood by those skilled in the relevant art that damping is but one of numerous methods to be employed for solving such noise and vibration problems. See for example: "Control of Noise and Vibration with Damping Materials," Ahis D. Nashif, Sound and Vibration, July, 1983.
Vibrations occurring in ranges over about 500 hz were considered filterable because in the past they were out of the signal range but as actuators were needed to operate in that range, the prior arts teachings of shifting the frequency of vibration upward were useless, thus a method of damping had to be found.
One method of damping vibration in a plane parallel to the disk recording surface has been taught by U.S. Pat. No. 4,408,283. In that patent, a pair of sidebars were attached by a thin strip of elastomeric adhesive to an arm of the transducing head supporting structure.
U.S. Pat. No. 4,144,466 describes a damping means for use in a voice coil-type linear actuator. In that patent, an elastomeric layer is arranged concentrically between two cylindrical rings. In that patent, auxiliary stiffening means are also required, in the form of beams and slots perpendicular to the longitudinal motion of the actuator.
In U.S. Pat. No. 4,144,466, attempts were made to apply unconstrained and constrained damping layers to the carriage or the coil itself without success (Lines 27 to 37).
The invention taught by the instant application however, provides for just such an arrangement. None of the prior art suggests the use of fins slotted with "H" shapes as described herein, nor their use in conjunction with applied layers of elastomeric material and stiffening plates to dampen the longitudinal resonances and other noise of voice coil actuators, as is taught here. The concept of slots allowing relative motion and application of this to damping in the form presented herein is a completely new idea.